Short cycling questions

mel rowe

Ran into a problem while helping a friend repipe his one pipe steam boiler properly. Added two vents for mains. Lowered an old 2 in. line that I found was functioning as a dry return after the old boiler was replaced. The dry return was doing a good job of turning the basement into a sauna. Added a second tapping to the boiler and installing a drop header currently. The problem is that when we turned the boiler back on, it ran for about 30 sec. and shut off. Sometimes it came back on, sometimes not. He said that he had this problem for a long time. He just turned up the thermostat ( to about 80 ) I think. I was suspicious of the Pressurtrol being the culprit, but when I installed a 0-5 psi gage, it showed only a few ounces of pressure. When he sets the stat very high and with the heat anticipator setting also high, the boiler runs and is now feeding evenly through the system. It doesn't make sense that it could be the stat, which is an old Honeywell T87, because it ran at a higher setting. I'm still suspicious of the Pressurtrol and plan to check it out further and clean if required. Would appreciate ideas as to what to look for.